Lava Lake on Jupiter Moon Io Triggers 'Hotspots' Seen from Earth

New images of Jupiter's volcanic moon Io show "hotspots" happening in different areas of a volcanic lake. Even more surprising given the lake's small size: the images were taken from Earth.

The pictures of the lake, called Loki Patera, suggest the thermal activity may happen as lava on top of the lake crusts over and falls into the liquid below, triggering emissions visible from Earth in ground telescopes. Astronomers even managed to create a video of Jupiter's moon Europa casting a shadow on the lava lake based on their observations.

Astronomers have detected emissions from the Io's lava lake, which is 124 miles wide (200 kilometers) lake from our planet, but only as a single glow. Researchers got a better look with the Large Binocular Telescope on Mount Graham in southeastern Arizona. The telescope has two 8.4-meter mirrors gazing at the sky, 6 meters (20 feet) apart from each other. [See more photos of volcanoes on Io]

A Large Binocular Telescope image of Loki Patera, a lava lake on Jupiter's volcanic moon Io (orange), on top of an image of the same region by NASA's Voyager spacecraft several decades ago.

Credit: LBTO-NASA

"We combine the light from two very large mirrors coherently so that they become a single, extremely large, mirror," said lead author Al Conrad, a scientist at the Large Binocular Telescope Observatory, in a statement. "In this way, for the first time we can measure the brightness coming from different regions within the lake."

Two of the hotspots on Io are in a region called Colchis Regio, where a huge eruption took place a few months before the images were taken. It's possible the activity was associated with that eruption, researchers said.

These images of Jupiter's volcanic moon Io show how it appeared to the Large Binocular Telescope in December 2013 (left), with the hotspots compared to an actual map of Io (right) created using data from NASA's Voyager 1 and 2 probes, and the Galileo spacecraft.

Credit: LBTO-USGS

Images from the telescope's LMIRcam (Large Binocular Telescope mid-infrared camera) were combined and processed by computer to make the features pop out. More generally, examining Io in such detail will help prepare NASA for potential missions such as the Io Volcanic Observer, team member and astronomer Chick Woodward of the University of Minnesota said in the same statement.

"Studying the very dynamic volcanic activity on Io, which is constantly reshaping the moon's surface, provides clues to the interior structure and plumbing of this moon," he said. "Io's highly elliptical orbit close to Jupiter is constantly tidally stressing the moon, like the squeezing of a ripe orange, where the juice can escape through cracks in the peel."

These images show a comparison of how Jupiter's moon Io was expected to look through an 8-meter telescope (simulated view at left), and how it actually appeared in the final image using the Large Binocular Telescope Interferometer project.